1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device that is adapted for enabling an active control of backlight brightness for each of areas included in a screen. The present invention also relates to a method of controlling the liquid crystal display device.
2. Description of the Related Art
A liquid crystal display device is mostly fabricated in a transmission type where a backlight unit 12 is installed at the rear surface of a liquid crystal display panel 11 as shown in FIG. 1. The liquid crystal display panel 11 of the transmission type liquid crystal display device, as shown in FIG. 1, controls the transmissivity of the light incident from the backlight unit 12 in accordance with video data to display an image.
The backlight unit 12 includes a lamp, a light guide panel to convert a linear light from the lamp into a planar light, and an optical sheet such as a diffusion sheet and a prism sheet to increase the uniformity and efficiency of the light. The lamp of the backlight unit 12 generates a discharge within a discharge tube between an anode and a cathode in accordance with a tube current from an inverter 14 to generate a white light.
The inverter 14 converts a DC power from a power source 13 into an AC power and boosts the AC power to generate the tube current.
Generally, the brightness of the backlight unit 12 is fixed. Because of this, the liquid crystal display device has lower brightness than the related art cathode ray tube CRT, its maximum brightness is fixed, and its contrast ratio is low. Thus, there is a problem in that the display quality of the related art liquid crystal display device is low.